The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it may be described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.
Nitric oxide (NO) and nitrogen dioxide (NO2) are noxious components of combustion exhaust streams. Many catalysts for abating NO and NO2 (NOx) produce undesirable products, such as nitrous oxide (N2O) or ammonia. Direct decomposition reactions, in which NOx is converted directly to N2 and O2 are known, but catalysts for direct decomposition frequently have low activity and/or selectivity.
Further, most conversion catalysts have little-to-no activity at low temperature, such that NOx is not converted during vehicle “cold start” conditions, when exhaust and converter temperature are low. Passive NOx adsorbers, which retain NOx at low temperature and release it at higher temperature, can minimize this issue.
Accordingly, it would be desirable to provide improved catalysts for direct decomposition of NOx, having high activity and selectivity, and improved NOx adsorption materials.